How Are Search Engines So Fast?

You’re looking for a file, and you know
that you just saved it. You know where you hoped this file was saved,
but you just don’t see it. So you try searching your computer,
and end up really frustrated. This paper is due in ten minutes, and your
computer is taking its sweet time searching. And you know you have the right filename
because you just saved it. So you ask your friend Google
where Word saves temporary files, just in case your computer
did something weird. And in the blink of an eye, Google gives you
an ordered list of relevant results. Google’s computers looked through
trillions of Web pages, ranked their relevance to your specific problem,
and listed them in order for you. Meanwhile, your computer keeps spinning away,
taking thousands of times longer to search a database a million times smaller than Google’s. So how does Google do it? You might assume that Google’s computers
are just faster than yours, and that’s probably true. But computing power isn’t the main reason
for Google’s impressive speed. Instead, it comes down to their famous algorithm. An algorithm is just any kind of procedure
that you follow in order to accomplish something. And with Google or any other search engine,
the algorithm is what turns your search into pages of results. The algorithm can work so fast
because the search engine doesn’t actually look through those trillions of pages
in that split-second between your search and the results showing up on your screen. That would take way too much time,
and this isn’t the dial-up era anymore. We want our results now. Search engines don’t look through
all those pages when you search because they already did. A search engine’s computers
are constantly crawling the Web. They follow links from site to site, creating
gigantic lists of which pages have which words, how many times those words appear on each page,
how important those pages are to the rest of the internet,
and all kinds of stuff like that. The exact way a search engine decides which
results to show you is generally a secret, since they want to stop sites
from gaming the system so they’re higher in the search results. But it all depends on how these gigantic lists
are sorted and combined into what’s called an index, which is a lot like the index
you’d find in the back of a book. When you search, the search engine’s computers
just check the index, find the entries that are most relevant, and then send them
back to you in the right order. This might sound more complicated than
searching the pages themselves each time, but think about how much easier it is
to find something in the book’s index than it is to flip and skim through every page
to find what you’re looking for. The index is faster because whoever made it
did all the work for you by putting the book’s topics in a nice, orderly list. And their hard work is worth it, because the
index lets you find whatever you want way faster than you could’ve otherwise. Google’s computers also put a ton of time
and effort into making the index, but all that effort’s worth it. The index dramatically speeds up each of the
roughly forty thousand searches that Google answers every single second. So why doesn’t your home computer
or laptop make an index if it’s easier to search through than files themselves? Well, some modern computers do, which lets
them search for files pretty quickly. And those that don’t can generally make
an index if you ask nicely. Or, really, if you change the right setting. But some people tell their computers not to
bother making an index, because making and maintaining an index takes time and
computer power that can slow a computer down. If you search without an index,
your computer pretty much has to go through each of those files
to see if it has what you’re looking for, which is why searching a computer
can be so painfully slow sometimes. And that’s why you’re watching your ten
minutes tick away as your computer asks each and every song you own if it’s your term paper. Thanks for watching this episode of SciShow, which was brought to you by
our patrons on Patreon. If you want to help support this show,
go to, and don’t forget to go to and subscribe!

100 thoughts on “How Are Search Engines So Fast?”

  1. The search functionality in windows is really, really bad. It's ridiculous. A program that does it better is Everything. It shows results in the blink of an eye, like windows should have been doing.

  2. The fact that there's a reverse index is, like, the least interesting part of a search… The cool part is the fact that the index is so big it can only fit on a cluster, and every search is a concurrent, distributed query.

    Seriously – every time you run a search, for a small fraction of a second you own an entire cluster. That is the cool part.

  3. Fuck Google, they ruined Youtube and also treat me like a baby (not allowing me to view X-rated pics). Bing it is!

  4. She could of emphasized the fact that google basically makes a copy of the www (minus the images and video) and makes a 'local query' when upchucking info to the user. the indexing.. But she got it correct.

  5. If you want to improve your computer's search speed, index your drive every once in a while. Right click on the drive in My Computer, click Properties, and check the Indexing checkbox.

  6. if you think your dislike is because of her voice, but like hank's videos then youre just sexist. hes just as fucking annoying just in a different way; no offence hank and olivia i love you both. but seriously theres a double standard to the claims of which videos are annoying and which arent.

    maybe everyone should just leave the presenters alone.

  7. Someone has to say it… The Mac. The Mac has it's files indexed, by default, all the time. It finds stuff super fast. The index is built incrementally, so it doesn't slow the computer down (unless the whole index needs to be rebuilt).

  8. This is actually interesting. I like these random topics. Wish Olivia did SciShow Space tho.. I would love to listen to her talk about space related topics. Other than Hank..shes my favorite Host.

  9. On July 2012 scientists at CERN announced that they had found a new particle, expected to be the elusive and important Higgs boson. It was one of the biggest scientific moments in recent physics and scientists all around the world were amazed by the incredible and promising findings. Many people saw that the slides used to present this major discovery were written in a funny Comic Sans font. Some of them complained for the bad aesthetics, maybe because that was the most important thing that their brain noticed and understood.

  10. this is really over simplification right here. The "index" is only a small part of what makes a search so fast

  11. Why does everyone care about the most unimportant things. You came here to listen to facts, not to see a visual presentation.

  12. Though it's Olivia, I liked this video. I think she's improving (or am I getting used to it ?!) 🤔

  13. ugh, I just spent hours of my life optimizing crap like this at work. Now I came home and get greeted with this?? Gee, thanks a lot.

  14. Unfortunately google's biggest strength (ranking according to importance) is also it's biggest weakness as it encourages populism to replace truth.

  15. Or….just make sure you first saved your copy somewhere you usually file it, like a "this is for school crap" folder

  16. There's also the fact that the entirety of Google's search index is stored in RAM on Google servers (the higher-ranked sites indices are stored in multiple locations too), while your computer is digging through files on a SSD or, even worse, a spinning hard drive, both of which are significantly slower than RAM.

  17. ZtreeWin emulate an old DOS program, X-tree, while taking full advantage of 32 bit/64 bit virtually limitless computers. Where are the biggest files? Where are the most recent files? Which folders contain the largest number of files. Nothing hidden, find cache maintained by your browser, any temporary files created by Windows beside the "windows/temp/" location and more.
    Once you scanned the entire hard drive, the next search takes less than 1 second for a typical 1 million files computer.
    I have no financial connection with the author. I just want to help non linux users.

  18. I like the content but she makes my ears hurt. I had to turn my laptop down to 6 so maybe she's saving me power.

  19. Overall, I much prefer Windows to MacOS, but one thing I gotta give to Apple is that Spotlight is infinitely better than the built-in Windows search. I've spent a lot of time making sure my indexing options are set to be helpful, but that does not help the search function be helpful.

  20. Ok SciShow we need more Olivia! I don't care how, give her her own channel or something. Chop chop… You introduced her to us so now take the responsibility!

  21. You got some shiny metallically snot hanging out of your nose. Really unattractive. Don't you own a mirror?!

  22. It's enabled on W10 by default if you have a SSD you don't notice any lag or downtime but with and old classic hdd it can hog its all spinning resources.

  23. thanks guys for the video , try to make more videos about information technology and computer traffic and routing.

  24. Windows search is slow because it is garbage, not because it searches file names. Search everything does the job instantly if you have indexed, within about 20 seconds if you have not.

  25. Google search operators are really awesome. If anyone know how to use it properly; then he can search google like a boss/professional/hacker. Thank You SciShow

    Tutorial Heaven

  26. pro-tip, the setting you guys are looking for can be accessed by right clicking on the C drive and clicking the box that says something like "Index my files" but she's right, it does slow down your computer. Not all the time, just when it needs to edit the contents of the hard drive. It won't slow down you game of WoW, but it will probably slow down any game that stores local files, and it will make installing and updating applications slower.

  27. if someone uses grep (in a bash shell or similar), it also finds stuff drastically faster than using Windows Search; and grep doesn't use any sort of index either…

  28. The reason why search engines are fast is because they cache results in memory. It's NOT because they index the results. That's important too, but not the main reason why you get your results instantly. For more complex queries, google does not cache the results, and thus, it takes more time to retrieve them.

  29. thx for this awesomely ha bisky vid i loved this a lot and i dont really have much on my laptops/computers ever

  30. Well , you were nore intersting to me than the whole point of the video. I wonder which index i should use to find you.

  31. Very well, but this doesn't explain how google searches the internet for specific phrases so fast, as when we use the "" function. These will not be indexed.

  32. Hey, You! Yes, You over there at where ever your SciShow studio is. STOP WITH THE GODDAMN PATREON THING, IT IS SO F*CKING ANNOYING.

  33. Guys, this is why you should clean your registry often and defrag often. The computer's search works a similar, albeit simpler, way. It looks through the master file table (MFT) and registry (regedit.exe). On my computer, without cleaning registry of defragging for 2 weeks, it takes 8 minutes to search all files. Just after cleaning registry and defragging, the search takes just 15 seconds.

  34. It's STILL a miracle lol, I often find myself sitting in front of my monitor in amazement at the greatest library ever created and the sheer size of the whole thing. I wonder what my grandchildren be using?, we are so lucky to live in times like these, my mothers time she tells me life was colorless and being working class there was little or nothing to actually do. Being British working class she told me that on long nights of nothing {not even radio, only crystal sets and they were not common } when it became dark { only gas mantle lights then } even sitting in front of the fire and watching the flames dance had a calming effect on the whole family and made you ready for bed. We really cant even imagine that can we

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